Summary The objective of this proposal is to identify causal genetic defects in patient-specific congenital heart disease (CHD) with the aim of providing specific genetic information and underlying mechanism for future targeted intervention by personalized treatment of CHD patients, an essential component of the `bedside-to-bench-to-bedside' concept in congenital and other heart disease treatments. We propose two complementary approaches: (1) gene discovery based on cardioblast expression profiles from wildtype and mutant Drosophila hearts with subsequent functional testing and integration into a genetic regulatory network of cardiogenesis that will link core cardiac transcription factors to heart morphogenesis; (2) genetic modeling of CHD gene candidates, identified from 2 cohorts of patient-derived genomic and transcriptome sequencing data, using our Drosophila heart model. Cohorts include one with copy number variations (CNV) and another based on genes' mutation frequency from patients with Tetralogy of Fallot (TOF). Initial new CHD gene discoveries will immediately be be integrated into known pathways, such as genetic interactions with tinman/NKX2-5, or be categorized as `new' for further testing and network integration. Aim 1 is to continue the construction of a gene network of cardiac morphogenesis based on gene discovery in Drosophila, whereas Aim 2 is to identify new causal CHD genes and their mechanisms. Our goal is not to approximate a specific CHD phenotype in the fly, but rather (a) to harness the power of the Drosophila heart model we have created, where gene discovery and testing for interactions between multiple genes can be achieved efficiently, and (b) to identify conserved genes and pathways that are relevant to CHD.